Hydrocarbon conversion process



United States Patent C) 3,239,577 HYDROCARBON CONVERSION PROCESS HermanS. Bloch, Skokie, George R. Donaldson, Barrington, and Vladimir Haensel,ll-lins'dale, 111., assignors to Universal Oil Products Company, DesPlaines, llL, a

corporation of Delaware N Drawing. Filed Oct. 23, 1964, Ser. No. 406,173

Claims. (Cl. 26tl683.47)

This application is a continuation-impart of my copending applicationSerial No. 307,364, filed September 9, 1963, now abandoned.

This invention relates to the preparation of branched chain paraffinhydrocarbons containing at least 5 carbon atoms per molecule.

An object of this invention is to provide a novel hydrocarbon conversionprocess for preparing branched chain paraifin hydrocarbons containing atleast 5 carbon atoms per molecule.

A further object of this invention is to provide a novel hydrocarbonconversion process for preparing a branched chain parafiin hydrocarboncontaining at least 5 carbon atoms per molecule from a starting materialcomprising a paraifin hydrocarbon of at least 4 carbon atoms permolecule at very mild hydrocarbon conversion reaction conditions.

Production of highly-branched chain parafi'in hydrocarbons having highanti-knock properties and therefore suitable for use in automotive andaviation fuels is of considerable importance in the petroleum refiningindustry. Furthermore, the introduction of automobile engines of highcompression ratio has necessitated the utilization of high anti-knockfuels in these engines to obtain maximum horsepower output therefrom.Thus, the demand for higher and higher octane number fuels has led tothe need for increased quantities of highly-branched chain paraffinichydrocarbons of high anti-knock values. A convenient source of suchhighly-branched chain paraffinic hydrocarbons is the catalyticconversion of less highly-branched chain paratlinic hydrocarbons. Forexample, normal butane and normal pentane have been isomerized toisobutane and isopentane, respectively, by various prior art processesutilizing either liquid or vapor phase. However, it is well known in theart that cracking occurs along with isomerization, and that thiscracking increases with increasing molecular weight of the hydrocarbonreactant. A process for the preparation of branched chain paraifinhydrocarbons containing at least 5 carbon atoms per molecule isparticularly attractive when the starting material can be converted atvery mild conversion conditions by means of a chain reaction typemechanism, hereinafter described in the example in detail, into a highanti-knock hydrocarbon fraction. It is therefore an objective of thisinvention to provide such a process which will yield the desiredbranched chain paraflin hydrocarbon containing at least 5 carbon atomsper molecule.

Prior art processes for the isomerization of saturated hydrocarbons havetaught the utilization of various catalytic agents to accelerate thedesired molecular rearrangement at the conditions selected. Ordinarily,the catalytic agents utilized have comprised metal halides such asaluminum chloride, aluminum bromide, etc., which were activated byaddition of the respective hydrogen halide thereto. These catalyticagents are very active and effect high conversion per pass. However,this high activity is accompanied by many disadvantages. One of thegreatest disadvantages is the fact that these catalytic materials notonly accelerate isomerization reactions, but they also inducedecomposition reactions. These decomposition reactions are particularlydetrimental to the overall economics of an isomerization process sincethey cause a loss of a portion of the charging stock as well asincreasing catalyst consumption by the reaction of fragmental materialwith the catalytic agent to form sludgelike materials. The process ofthe present invention overcomes these disadvantages by utilization ofmore recently developed catalysts, and thus, the use of this novelhydrocarbon conversion process along with these catalysts results in theattainment of a hydrocarbon conversion reaction in which a high octanebranched chain parafiin hydrocarbon containing at least 5 carbon atomsper molecule is obtained.

One embodiment of this invention provides a process for the preparationof branched chain parafiin hydrocarbons containing at least 5 carbonatoms per molecule which comprises passing to a reaction zone containinga conversion catalyst at conversion conditions a paraifin hydrocarbon ofat least 4 carbon atoms per molecule in admixture with not more than0.05% by Weight of halide promoter and not more than 3% by weight ofolefin activator, contacting said catalyst with said admixture in thepresence of isobutane, withdrawing from said reaction zone a reactionzone efiluent, continuously recycling at least a portion of saideffluent to said reaction zone for further contacting with saidcatalyst, and subsequently recovering the resultant product.

A further embodiment of this invention provides a process for thepreparation of branched chain paraffin hydrocarbons containing at least5 carbon atoms per molecule which comprises passing to a reaction zonecontaining a conversion catalyst comprising a refractory oxide, aplatinum group metal and combined halogen at conversion conditions aparaffin hydrocarbon of at least 4 carbon atoms per molecule inadmixture with not more than 0.05 by weight of halide promoter and notmore than 3% by weight of olefin activator, contacting said catalystwith said admixture in the presence of isobutane, withdrawing from saidreaction zone a reaction zone efiluent, continuously recycling at leasta portion of said efiiuent to said reaction zone for further contactingwith said catalyst, and subsequently recovering the resultant product.

A specific embodiment of this invention provides a process for thepreparation of isopentane which com prises passing to a reaction zonecontaining a conversion catalyst comprising a refractory metal oxide, aplatinum group metal and combined halogen, isobutane in admixture withnot more than 0.05 by weight of isopropyl chloride and not more than 3%by weight of propylene, contacting said catalyst at conversionconditions including a temperature of from about 0 to about 65 C. and apressure of from about atmospheric to about 200 atmospheres with saidadmixture, withdrawing from said reaction zone a reaction zone efiluent,continuously re cycling at least a portion of said eflluent to saidreaction zone for further contacting with said catalyst, andsubsequently recovering isopentane.

A still more specific embodiment of this invention provides a processfor the preparation of isopentane which comprises passing to a reactionzone containing a conversion catalyst comprising alumina, platinum andfrom about 5% to about 20% by weight of aluminum chloride impregnatedthereon at a temperature of from about 425 to about 625 C., isobutane inadmixture with not more than 0.05% by weight of isopropyl chloride andnot more than about 3% by weight of propylene, contacting said catalystat conversion conditions including a temperature of from about 0 toabout 65 C. and a pres sure of from about atmospheric to about 200'atmospheres with said admixture in the presence of from about 0.25 toabout 10 moles of hydrogen per mole of hydrocarbon, withdrawing fromsaid reaction zone a reaction cyclohexane, etc.

zone efiduent, continuously recycling at least a portion of saideifiuent to said reaction zone for further contacting with saidcatalyst, and subsequently recovering isopentane.

The process of this invention is particularly applicable to theconversion of saturated hydrocarbons including both parafilns andcycloparatfins. Suitable parafiin hydrocarbons are those containing atleast 4 carbon atoms per molecule including normal butane, isobutane,normal pentane, isopentane, normal hexane, 2-.methylpentane,3-rnethylpentane, normal heptane, Z-methylhexane, 3 methylhexane, normaloctane, etc., and cycloparafiins such as the alkylcyclopentanes andcyclohexanes including methylcyclopentane, dimethylcyclopentane,cyclohexane, methylcyclohexane, dimethylcyclohexane, .ethyl- The processis also applicable to the conversion of mixtures of paraifins such asthose derived by fractionation of straight-run or natural gasolines, orin the raffinate produced by extraction of aromatics from a hydroformednaphtha. Aromatics absent from the feed stock to the present process,and it is preferred that the feed containbranched as well :as normalparafiins.

We believe that under the conditions utilized and with the catalystemployed, a chain reaction mechanism occurs whereby, for example, from 2to 4 isobutane molecules become involved per propylene molecule, asshown in the accompanying series of reactions in Table I whichillustrate a specific embodiment of this invention. Underlined moleculesare those which undergo net consumption or production; all othermolecules or ions are assumed to be intermediate.

TABLE I (22) Etc.Repeat from (7) onward Summary of Cycle (7)-(21)Inclusive: s s+ 4 1o" 5 12+ 6 14 In this series, the 15 reactionsbetween the horizontal f are preferably lines in Table I represent acycle which may be sum ,This particular cycle yields 433% by weight ofliquid i product based on the propylene charged. Other cycles could bewritten to show somewhat greater or somewhat lesser yields and to showthe formation of other branched f chain paraflin hydrocarbons containingat least 5 carbon atoms per molecule.

Various conversion catalysts are utilizable within the.

support may be selected from various diverse refractory oxidesincludinggsilica, alumina,silica-alumina,v silicaalumina-magnesia,silica-alumina-zirconia, silica-zirconia,

etc. Depending upon the method of preparation and upon the treatment ofthe support-thereafter, these various supportswill have surface areasranging from about 25 to about 500. square meters per gram. In some ofthese supports, the acid-actin'gfunction- .is inherently present, aswhen silica-alumina. is used as the-support; The amount of effectivenessof this acid-acting-function is then controlled by the quantity ofsilica which ,is. combined with the alumina, and by the :treatment ofthe silica-alumina, particularly by calcination, prior to or aftercompositing the hydrogenation component: therewith. Of'the varioussupports, alumina is:preferred, and

particularly gamma-alumina having a surface-area of from about to about450 square meters per: gram;. Whengamma-alumina is utilized as thesupport, the

acid-acting function can be added to. the, catalyst by the incorporationtherein .of what is known :in the art' as com bined halogen.

on the alumina. Of the various halogens which may be utilized, bothfluorine and chlorine'can be utilizedsatisfactorily. Thus, a'suitablealumina-typecatalyst to be utilized in the. processzof-the presentinvention may comprise about 0.3 'by weight of fluorine and about 0.3%

by weight of :chlorine incorporated therein. Another suitable catalystfor use in:the process of the present invention would comprise analumina-type catalyst where the combined halogen incorporated .with thealumina support is fluorine, and this fluorine may. be utilized in anamount of from about 2.5% to about 74.5 by weight.-

The composite will then have the desiredhydrogenation 0.01% to about:10% by weight based on the: weight of the support. With .the preferredplatinum group metals, .particularlyplatinum, the quantity utilizedwillrange from about 0.01% to about-2% by weight. One typical catalystcomprising platinum. combined halogen, and

alumina foruse in the process of thisinvention therefore a will containabout 0.375% platinum,=about 4.5% combined fluorine, and alumina.

Because of equilibrium conditions and because itis often desirableand/or advisable to carry out the conversion at the lowest possiblereaction temperature, cataa lysts may also'be prepared by impregnatingcomposites suchas hereinabove' described with a metalhalide of theFriedel-Crafts type at elevated temperatures.- Various Friedel-Craftsmetal halides may be :utilized but. not necessarily with equivalentresults:

aluminum chloride, antimonypentachloride', beryllium chloride, ferricbromide, ferric chloride, gallium trichloride, stannic bromide, stannicchloride, titanium tetrabromideytitanium tetrachloride, zinc bromide,-zinc chloride, and zirconiumchloride. Of these'Friedel-Craftsmetalhalides, the Friedel-Crafts aluminum halides are preferred, andaluminum chloride is particularly preferred. While the, catalysts are.prepared from Friedel- Crafts metal halides, they do. not contain anyfree Friedel- Crafts metal halides as priorart catalysts of this generaltype have contained. During the preparation of The amount of combined,halogen can be varied from about 0.01 to about.8% by weight based.

Examples of such. Friedel-Crafts metal halides include aluminum bromide,

these catalysts at elevated temperatures, the Friedel- Crafts metalhalide appears to react with the refractory oxide and it is believedthat the Friedel-Crafts metal halide reacts with the hydroxyl groups onthe refractory oxide surface so that when the catalyst preparation iscompleted, the catalyst composite is free from Friedel- Crafts metalhalide. For example, an excellent lowtemperature conversion catalystparticularly preferred for use in the present invention can be preparedby impregnating from about 5 to about 20% aluminum chloride onto acomposite of platinum, alumina, and combined halogen at temperatures offrom about 425 C. to about 625 C. The final catalyst composite containsabout 38% of combined chloride, is free from aluminum chloride, and is aparticularly preferred conversion catalyst for preparing branched chainparaffin hydrocarbons containing at least 5 carbon atoms per molecule.

The feed to the reaction zone, namely the paraffin hydrocarbon of atleast four carbon atoms per molecule, is passed in admixture with notmore than 0.05% by weigh-t of halide promoter that is selected topromote the desired conversion reaction and preferably with not morethan 3% by weight of olefin activator which is designated to be a sourceof free radicals in the hydrocarbon conversion reaction and withbranched chain paraffin hydrocarbon of four carbon atoms per molecule,namely, isobutane, that is passed to the reaction zone at the same timeas the paraflin hydrocarbon feed. Concentrations of halide promotergreater than about 0.05 by weight (of the paralfin hydrocarboncontaining .at least 4 carbon atoms per molecule) are unnecessary, and,in fact, not desired inasmuch as the catalytic composites utilizable inthe present invention do not require large amounts of halide promoter tomaintain the activity of the catalytic composite nor do large amounts ofhalide insure the stability of the catalytic composite against undueaging. In fact, it is known that large amounts of halide promoter tendto detract from the catalytic activity of such catalysts andcorrespondingly, lower yields of product are obtained. Also, ashereinabove stated, the olefin activator utilized in the process of thepresent invention will not exceed 3 by weight of the paraffinhydrocarbon charge stock inasmuch as concentrations of olefin greaterthan about 3% would undergo hydrogenation and polymerization, therebyalso contributing to rapid catalyst deactivation.

Suitable halide promoters utilizalble in the present invention includealkyl halides including ethyl fluoride, npro-p-yl fluoride, isopropylfluoride, n-butyl fluoride, isobutyl fluoride, sec-'butyl fluoride, tertbutyl fluoride, etc, ethyl chloride, n-propyl chloride, isopropylchloride, nbutyl chloride, isobutyl chloride, sec butyl chloride,tertbutyl chloride, etc., ethyl bromide, n-propyl bromide, isopropylbromide, n-butyl bromide, isobutyl bromide, secbutyl bromide, tert-butylbromide, etc. Suitable olefin activators utilizaible in the presentinvention include propylene, l-butene, 2-butene, isobutylene, and highermolecular weight normally liquid olefins such as the various pentenes,hexenes, heptenes, ootenes, and mixtures thereof, and still highermolecular weight liquid olefins, the latter including various olefinpolymers having from about 9 to about 18 carbon atoms per moleculeincluding propylene trimer, propylene tetramer, propylene pentamer, etc.Cycloolefins such as cyclopentene, methylcyclopentene, cyclohexene,methylcyclohexene, etc. may also be utilized. Of the olefin activatorsfor use in the process of this invention, propylene is particularlypreferred.

The conversion process of the present invention is carried out atvarying conditions of temperature, pres-sure and space velocity. Thetemperature utilized will generally be dictated by the particularcatalyst selected. Thus, the temperature may range over a relativelywide range of from about 0 C. to about 200 C. although it isparticularly preferred to operate the process of the present invent-ionat mild operating temperatures of from about 0 C. to about 65 C. Thehigher temperatures are used especially if it is desired to effect thedesired conversion reaction without an olefin activator or in asituation where very small amounts of olefin activator are utilized. Thepressure will be selected so as to always insure at least a partialliquid phase in the reaction zone, and depending upon the particulartemperature utilized, will range from about atmospheric pressure toabout 200 atmospheres or more. Liquid hourly space velocities will rangefrom about 0.1 to about 20 or more. Hydrogen is utilized to minimizecracking and to maintain the surface of the catalyst in a substantiallycarbon-free condition. The quantity of hydrogen utilized will range fromabout 0.25 to about 10 moles or more of hydrogen per mole ofhydrocarbon. Hydrogen consumption will be exceedingly small, in therange of from about 30 to about cubic feet per barrel of hydrocarbonfeed.

The process of the present invention may be effected in any suitablemanner and may comprise either a batch or a continuous type operation. Aparticularly preferred method of operation comprises a fixed bed-typeoperation where the conversion catalyst is disposed as a fixed bedwithin the reaction zone. Other continuous types of operation which maybe used in this process include the compact moving bed-type of operationin which the bed of catalyst and the reactants pass either concurrentlyor counter-currently to each other in the reaction zone, and the slurrytype operation in which the catalyst is carried into the reaction zoneas a slurry in one of the reactants.

The following example is given to illustrate our invention but is notintroduced with the purpose of unduly limiting the same.

Example One specific example of the operation of the process with analumina-platinum-combined halogen catalyst is described herewith. Thecatalyst comprises 0.375% by weight platinum on a calcined gamma-aluminasupport which has been impregnated at about 538 C. with aluminumchloride and thereafter swept with a stream of dry nitrogen at the sametemperature to remove excess unreacted aluminum chloride so that thecatalyst contains about 5% by weight total combined chloride.

A combined feed comprising 200 grams per hour of isobutane and 2 gramsper hour of olefin activator, namely propylene, in admixture with notmore than 0.05% by weight of halide promoter, namely ppm. (0.01% byweight) of isopropyl chloride, is passed to the reaction zone containingthe above-described catalyst. The reaction zone is maintained at about25 C. and about 750 p.s.i.g. so as to insure at least a partial liquidphase in the reaction zone. The efiluent liquid is collected in areceiver and after a sufiicient quantity has accumulated, effluent fromthe receiver is recycled over the catalyst at a rate of about 2 gallonsper hour, while excess eflluent is discharged as product. There isformed from the above feed from 7 to 10 grams per hour of net liquidproduct comprising 55% pentanes (of which 77% are iso-pentane), 22%hexanes (of which 54% are neohexane and the remainder isomeric hexanes),12% heptanes and about 11% octanes.

It is evident that this liquid product, which amounts to 350500% byweight of the olefin feed, cannot be a simple propylene-isobutane alkylation product, but results from a series of reactions of the typediscussed hereinabove.

We claim as our invention:

1. A process for the preparation of isopentane which comprises passingto a reaction zone containing a conversion catalyst comprising arefractory metal oxide, a platinum group metal and combined halogen,isobutane in admixture with not more than 0.05% by weigh-t of isopropylchloride and not more than 3% by weight of propylene, contacting saidcatalyst at conversion conditions including a temperature of from about0 to about 65 C.

and a pressure of firom about atmospheric to about 200 atmospheres withsaid admixture, withdrawing from said reaction zone a reaction zoneeflluent, continuously recycling at least a portion of said efiiuent tosaid reaction zone for further contacting with said catalyst, and sub.

sequently recovering isopentane.

2. .A process for the preparation of isopentane which comprises passingto a reaction zone containing a conversion catalyst comprising alumina,platinum and from about 5% to about 20% by Weight of aluminum chlorideimpregnated thereon at a temperature offrom aboutv 425 to about 625 C.,isobutane in admixture with'not more than 0.05% \by weight of isopropylchloride and not more than about 3% by Weight of propylene, contactingsaid catalyst at conversion conditions including a temperature of fromabout 0 to about 65 C. and a pressure of from about atmospheric to about200 atmospheres,

with said admixture in the presence of from about 0.25

to albout-10 moles of hydrogen per mole of hydrocarbon, withdrawing fromsaid reaction zone a reaction zone .ef-

fluent, continuously recycling at least a portion of said efiluent tosaid reaction zone for further contacting with said catalyst, andsubsequently recovering isopentane.

said combined halogen is a mixture of chlorine and from.

about 0.3% to about 0.7% by weightoffiuo-rine; V 5. File process ofclaim 1 further characterized in that said-combined halogen is fluorinein an amountof from about 2.5 to about 4.5% by weight.

References'Cite'd by the Examiner UNITED; STATES PATENTS 2,425,2688/1947 Sensel 2'60683.75"' 2,908,735 10/1959 Haensel; 26068-3'.682,972,649 2/1961 Thomas etal. 260-458-353 1 PAUL M. OOUGHLA-N, PrimaryExaminer.-

ALPHONSO D. SULLIVAN, DELBERT GANTZ,

' Examiners.

1. A PROCESS FOR THE PREPARATION OF ISOPENTANE WHICH COMPRISES PASSINGTO A REACTION ZONE CONTAINING A CONVERSION CATALYST COMPRISING AREFRACTORY METAL OXIDE, A PLATINUM GROUP METAL AND COMBINED HALOGEN,ISOBUTANE IN ADMIXTURE WITH NOT MORE THA 0.05% BY WEIGHT OF ISOPROPYLCHLORIDE AND NOT MORE THAN 3% BY WEIGHT OF PROPYLENE, CONTACTING SAIDCATALYST AT CONVERSION CONDITIONS INCLUDING A TEMPERATURE OF FROM ABOUT0* TO ABOUT 65*C. AND A PRESSURE OF FROM ABOAUT ATMOSPHERIC TO ABOUT 200ATMOSPHERES WITH SAID ADMIXTURE, WITHDRAWING FROM SAID REACTION ZONE AREACTION ZONE EFFLUENT, CONTINUOUSLY RECYCLING AT LEAST A PORTION OFSAID EFFLUENT TO SAID REACTION ZONE FOR FURTHER CONTACTING WITH SAIDCATALYST, AND SUBSEQUENTLY RECOVERING ISOPENTANE.